Trochanter stabilising plate improves treatment outcomes in AO/OTA 31-A2 intertrochanteric fractures with critical thin femoral lateral walls

Abstract

Background: For AO/OTA 31-A2 fractures (A2 fractures) treated with dynamic hip screw (DHS), postoperative lateral wall fracture (PLWF) is thought to be a major cause of femoral medialisation and reoperation. Though trochanter stabilising plate (TSP) had been reported to have a good effect in preventing femoral medialization, its effects and indication in A2 fractures remain controversial. We hypothesized that TSP may improve treatment outcomes in patients with high risk of postoperative lateral femoral wall fractures. The purpose of this study was to investigate (1) the main risk factors predictive of PLWF in A2 fractures and, (2) whether TSP can improve treatment outcomes in patients with high risk of PLWF.

Methods: Two hundred and fifty-two A2 fractures treated with DHS or DHS and TSP (DHS-TSP) during January 2000 and June 2013 were enrolled in this study. Standard univariate and multivariate analyses were performed to determine statistically significant risk factors for PLWF in 205 patients who were treated with DHS alone. The risk factor found to be associated with PLWF was utilized to include 171 patients who were at high risk of PLWF. Standard univariate and multivariate analyses were performed to evaluate the effect of TSP on treatment outcomes.

Results: Lateral wall thickness was found to be the main risk factor for PLWF in A2 fractures. A lateral wall thickness of 2.24 cm was found to be the best cutoff point to determine which patients were at high risk for PLWF. In 171 patients with a lateral wall thickness less than 2.24 cm, patients treated with DHS-TSP had significantly decreased lag screw sliding distances, PLWF rate, and reoperation rate (P=0.028, <0.001 and P=0.003, respectively) compared to the corresponding values of those treated with DHS alone. In the multivariate analysis, TSP decreased the reoperation rate by 13 times compared to that of patients who were treated with DHS alone.

Conclusion: Lateral wall thickness is the main risk factor for PLWF in A2 fractures treated with DHS. Use of TSP in A2 fractures with critical thin lateral wall thickness <2.24 cm can significantly decrease the lag screw sliding distances, PLWF rate and reoperation rate.

Keywords: A2 fracture; Dynamic hip screw (DHS); Lateral femoral wall fracture; Lateral wall thickness; Sliding hip screw (SHS); Trochanter stabilizing plate (TSP); Unstable intertrochanteric fracture.